Song repertoires and sexual selection in the Red-winged Blackbird

Summary

The female choice and male-male competition hypotheses for the evolution of song repertoires were tested by studying repertoire size, pairing success, reproductive experience, and territory size in the Red-winged Blackbird. Analysis of these variables produced the following results:

1)

Male Red-winged Blackbirds with large song repertoires were more experienced and acquired more females than those with small repertoires.

2)

The apparent preference of female redwings for males with large repertoires was an indirect consequence of the correlation between repertoire size and amount of reproductive experience.

3)

Examination of males lacking reproductive experience indicated that large repertoires confer an advantage in competition for territories, and that females prefer males defending superior territories.

These results are consistent with the hypothesis that song repertoires in the Red-winged Blackbird evolved in response to male-male competition.